Suction pipe heating by exhaust gas

ABSTRACT

In a four-cylinder combustion engine, the heating of the suction pipe by exhaust gas is carried out by a device wherein a separate branch conduit is branched off from the exhaust piping of three cylinders and opens into a preheating conduit having a common wall with the suction pipe.

United States Patent Inventor Franz Hank Ingolstadt, Germany Appl. No.726,976 Filed May 6, 1968 Patented Mar. 16, 1971 Assignee Auto UnionG.m.b.l-1.

Ingolstadt, Germany Priority May 17,1967

Germany P 15 76 445.1

SUCTION PIPE HEATING BY EXHAUST GAS 1 Claim, 8 Drawing Figs.

US. Cl. 123/ 122,

123/52 Int. Cl ..F02m 31/00 Field of Search 123/ 122 (A), 2, 52 (M), 52(MB), 52 (MV), 52 (ML) [56] References Cited UNITED STATES PATENTS2,757,652 8/1956 Rothwell 123/52MV 3,019,781 2/1962 Kolbe 123/52M3,363,610 1/1968 Massarotti.. 123/52M 1,476,315 12/1923 Wilsey 123/122A2Primary Examiner-Laurence M. Goodridge Attorney Richards & GeierABSTRACT: In a four-cylinder combustion engine, the heating of thesuction pipe by exhaust gas is carried out by a device wherein aseparate branch conduit is branched off from the exhaust piping of threecylinders and opensinto a preheating conduit having a common wall withthe suction pipe.

Patented March 16, 1971 3,570,462

3 Sheets-Sheet 1 Fig. I

lnvemar: FTHauK ATT'OYLNGHS Patented March 16, 1971 3 Shasta-Sheet 2lave/liar: F. Haw dhmw gw ATTOn-NEBS Patant ad 'Mareh 16, 1971 3,570,462

5 smawsnm a FIG? INVENTOR FRANZ HAUK SUCTTGN lPllPlE HEATING BY EXHAUSTGAS This invention relates to the heating of the suction pipe of afour-cylinder combustion engine by exhaust gas. In prior art devicessuch heating is carried out by a separate branch conduit branched offfrom the exhaust piping of two cylinders and opening into a preheatingconduit having a common wall with the suction pipe. More specifically,branch conduits are branched off from the exhaust pipes of the first andlast cylinders and are guided to the preheating conduit. The usualignition sequence is l-3-4-2 so that in operation the last cylinderfollows the first cylinder by a full rotation of the crankshaft. If therevolving speed is slow, the preheating conduit can be supplied withexhaust gas through one branch conduit, the gas being removed throughthe other conduit. When the rpm. are higher, the gas impulses in thebranch conduits follow each other so quickly that detrimental swingingstake place. Then the exhaust gas does not flow any more through thepreheating conduit with high speed, since it is braked by acounterswinging from the other branch conduit and thus loses the speedwhich is necessary for the heat exchange. 1

There is the additional drawback that a preheated mixture is alsosupplied to a heated machine running with a low speed, whereby thismachine can develop self-ignition or bell sounds in this condition.Furthermore, the preheating of the suction pipe to the operatingtemperature consumes a comparatively long time, since the heating can becarried out only by exhaust gases from branch conduits of two cylinders.

An object of the present invention is the provision of suction pipeheating which will quickly heat the suction pipe at a cold start andwill not cause any trouble by overheating the sucked-in mixture when themotor is operationally warm.

Other objects of the present invention will become apparent in thecourse of the following specification.

In the accomplishment of the objectives of the present invention it wasfound desirable to provide a third branch conduit branching from theexhaust pipe of a third cylinder and opening into the preheatingcircuit. Thus three exhaust conduits will be used for heating thesuction pipe, so that the suction pipe will be heated to operatingtemperature within a short time. Not only is the amount of exhaust gasused for the heating increased, but the flow conditions are alsoimproved, so that exhaust gases flow past the wall of the suction pipewith greater speed and transmit to it a correspondingly large amount ofheat. In accordance with the present invention exhaust gas flowing outof a branch conduit has at its disposal two branch conduits for theoutflow. In one of these two conduits, gas swingings are favorable forthe outflow, so that when the third branch conduit is open, a largeamount of hot gas flows with great speed along the wall of the suctionpipe throughout substantially the entire range of revolutions and thusheats the suction pipe within a short time to the operating temperature.

The suction pipe heating operates with great efficiency, particularlywhen the branch conduits belonging to the first cylinder and the thirdcylinder are alwaysconnected with the preheating conduit, while thebranch conduit belonging to the second cylinder can be connected withthe preheating conduit by a flap valve which is preferably actuateddepending upon temperature by a bimetallic strip. After the closing ofthe valve, the gas currents in the branch conduits are braked andprevent an overheating of the suction pipe. The valve is preferablyactuated by the bimetallic strip in a manner known per se, so that it isclosed when the suction pipe is operationally warm and is open when thesuction pipe is cold. When the machine is operationally warm, there isthe advantage that as soon as only one valve and thus only one supplyingpipe are closed, the other two supplying pipes which are provided withexhaust gas quickly, one after the other, effectively hinder a flowthrough the preheating conduit, so that the preheating conduit will notbecome too warm.

In practice, the suction pipe heating serves only the purpose ofbringing the suction pipe to the operating temperature and does notinfluence the operation of the motor in the operationally warmcondition.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawings,'showing by way of example, a preferred embodiment of the inventive idea.

In the drawings:

FIG. 1 illustrates the drive of a four-cylinder, four-cycle-seriesinternal combustion engine.

FIG. 2 is a diagrammatic top view of the engine shown in FIG. ll,illustrating the conduits through which exhaust gases flow.

FIG. 3 is a front view illustrating an embodiment of the presentinvention.

FIG. 4 is a section along the line IV-IV of FIG. 3.

FIG. 5 is a section through the admission valve of the first cylinder.

FIG. 6 is a section through the exhaust valve of the first cylinder.

FIG. 7 is a section along the line VII-VII of FIG. 3.

FIG. 8 is a section along the line VIII-VIII of FIG. 3.

The usual four-cylinder-series internal combustion engine is providedwith cylinders designated as l, 2, 3 and 4 in FIG. I. The pistons in thecylinders 1 and 4 are located in the upper dead center position and thepistons of the cylinders 2 and 3 in the inner dead center position. Thefiring order is l-34-2. Thus the exhaust gas leaves the cylinder 3 laterby one-half of the revolution of the crankshaft than the cylinder 1, andearlier by a whole revolution of the crankshaft than the cylinder 2.Each cylinder 1, 2, 3 and 4 is provided with a separate exhaust valve 5and a separate admission valve 6 (FIG. 2). Exhaust conduits 7, 7a, 7band 70 extend from the exhaust valves 5 and out of the cylinder head.Separate branch conduits 8, 9 and 10 branch off the exhaust conduits 7,7a and 7b of the cylinders l, 2 and 3. The branch conduits 8, 9 and 10as well as the exhaust conduits 7, 7a and 7b can be cast in the cylinderhead; the branch conduits leave it from the side which is opposite tothe side from which the exhaust conduits extend.

The branch conduits 8, 9 and 10 open into branch conduits 8a, aa and 100which are cast in one piece with the suction pipe 11 (FIG. 3). Thebranch pipings i2, 13, 14 and 15 of the suction pipe 11 extend into thecylinders 11, 2, 3 and 4. The branch conduits 8a, 9a and 10a extend intoa preheating conduit 16 which has a common wall 17 with the suction pipe11 (FIG. 4). The branch conduit can be connected with the preheatingconduit 16 by a flap valve 18 which is operated by a bimetallic strip insuch manner that the valve is open when the machine is cold and isclosed when the machine is warm. The exhaust conduits 7 and 70 open intoa pipe 19 and the exhaust conduits 7a and 7b open into a pipe 20. Thepipes 19 and 20 extend into a collecting pipe 21 which conducts theexhaust gases into an exhaust box 22.

In operation, when the' cold internal combustion engine is started, hotexhaust gases flow out of exhaust conduits 7, 7a and 7b and the branchconduits 8, 8a, 9, 9a, 10, and 10a into the preheating conduit to sothat they heat through the wall 17 the suction pipe 11 and the fuel-airmixture flowing therethrough. The exhaust gases flowing into thepreheating conduit 16 can leave it either through the branch conduit 90or through the branch conduit lfla, depending upon the number ofrevolutions with which the machine runs and the swingings of the exhaustgas moving in the branch conduits 9a and lfia. The exhaust gas will flowthrough the branch conduit having the smallest counterpressure.

lclaim:

l. A four-cylinder in-line engine operable in the ignition sequence 1-3-4-2 or 1-2-4-3 each of the cylinders having a separate admissionvalve and a separate exhaust valve, separate exhaust conduits cast inthe cylinder heads and each having one end connected to each separateexhaust valve, three branch conduits, each of said three branch conduitsbeing cast in a separate cylinder head and communicating with a separateexhaust valve and with a separate exhaust conduit, a preheating conduit,three other branch conduits, each of said three other branch conduitshaving one end connected with a separate first-mentioned branch conduitand another end connected with said preheating conduit, a suction pipehaving a common wall with said preheating conduit and having branchpipings extending into the four cylinders, a thermostatically operatedflap valve located in the central one of said three other branchconduits and connecting said central one of the three other branchconduits with said preheating conduit, an exhaust box and pipesconnecting the first-mentioned exhaust conduits with said exhaust box,whereby when said valve is open a part of the exhaust gases flowsthrough the exhaust conduit of the exhaust valve which is open at thetime while another part of the exhaust gases flows through said

1. A four-cylinder in-line engine operable in the ignition sequence 1-3-4-2 or 1-2-4-3, each of the cylinders having a separate admissionvalve and a separate exhaust valve, separate exhaust conduits cast inthe cylinder heads and each having one end connected to each separateexhaust valve, three branch conduits, each of said three branch conduitsbeing cast in a separate cylinder head and communicating with a separateexhaust valve and with a separate exhaust conduit, a preheating conduit,three other branch conduits, each of said three other branch conduitshaving one end connected with a separate first-mentioned branch conduitand another end connected with said preheating conduit, a suction pipehaving a common wall with said preheating conduit and having branchpipings extending into the four cylinders, a thermostatically operatedflap valve located in the central one of said three other branchconduits and connecting said central one of the three other branchconduits with said preheating conduit, an exhaust box and pipesconnecting the first-mentioned exhaust conduits with said exhaust box,whereby when said valve is open a part of the exhaust gases flowsthrough the exhaust conduit of the exhaust valve which is open at thetime while another part of the exhaust gases flows through said branchconduits, both parts of the exhaust gases flowing into said preheatingconduit and thence through some of said branch conduits, past the closedexhaust valves and through said pipes into said exhaust box, and wherebywhen said valve is closed no exhaust gases are transmitted into thepreheating conduit from the exhaust valve connected with said centralone of the three other branch conduits while exhaust gases from otheropen exhaust valves due to disturbances do not produce a continuous flowextending into the preheating conduit.